There's gotta be something wrong with the rating system..

A bit ago, I started trying really hard to get an S for Kha'Zix, because its my main. I haven't gotten one yet, so.. I went 18/1 a while back and got A. Seems fair right now, right? Not really. Then, I see a Yasuo player go 9/3. What do they get? S-. Where the is the logic, rito? Hello? I heard it compares with other players OF that champion. Maybe about once two months I'd see a decent Kha'Zix player, but hardly not even close to 18/1. I see Yasuo players VERY commonly. C'mon... I sure as hell don't have the time to get 20+ kills before the enemy team surrenders or my team ends it. I also don't want to be a black hole that sucks up every kill my team works for.